Mel Gibson was drawn back to directing by the “remarkable” true story of conscientious objector Desmond T. Doss who, in Okinawa during the bloodiest battle of WWII, saved 75 men without firing a gun, the star said in Sydney on Thursday.

The story of the ”army medic who wouldn’t touch a weapon but yet who wanted to be part of saving lives in the worst place on earth," was “inspirational” Gibson said, announcing that Hacksaw Ridge will be based at Fox Studios Australia and filmed throughout the state of New South Wales, with assistance from the local government.

The film, Gibson’s first turn behind the camera since 2006’s Apocalypto, is now in preproduction in Sydney. Principal photography starts on Sept. 5 and is expected to be completed in the second half of 2016.

“To walk into the worst place on earth and not have a weapon and walk amongst it and do his job as a Corps medic and save so many lives, it's remarkable,” he said.

Gibson said Doss was a very humble man, who "didn’t like to make a song and dance" about his achievements, and gave the rights to his life story to his church, which sold them after he passed away. He was awarded the Medal Of Honor, the only conscientious objector to do so. He also received two Bronze Stars and three Purple Hearts.

“I’ve picked up the thread where I left off since I last worked here. I’m so glad to be working here again, bumping into people I’ve known for years, decades," he said.

New South Wales deputy premier Troy Grant said Hacksaw Ridge would generate over 720 jobs and $19 million (AUS$26 million) in production expenditure. Details of any financial incentives were not given and it's unclear if the film will qualify for the 40 percent tax rebate offered to Australian productions under the federal government’s producer offset program.

Alongside Gibson, there are a number of Australians in the key cast and crew working on Hacksaw Ridge, including writer Andrew Knight, who has overhauled the original script by Robert Schenkkan. Knight co-wrote Russell Crowe's directorial debut, The Water Diviner. Gibson said Knight “has done a real slap up revision for us”.